/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate licenses this file
 * to you under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.planner.optimizer.rule;

import io.crate.metadata.Functions;
import io.crate.metadata.TransactionContext;
import io.crate.statistics.TableStats;
import io.crate.planner.operators.Filter;
import io.crate.planner.operators.LogicalPlan;
import io.crate.planner.operators.NestedLoopJoin;
import io.crate.planner.optimizer.Rule;
import io.crate.planner.optimizer.matcher.Capture;
import io.crate.planner.optimizer.matcher.Captures;
import io.crate.planner.optimizer.matcher.Pattern;

import static io.crate.planner.optimizer.matcher.Pattern.typeOf;
import static io.crate.planner.optimizer.matcher.Patterns.source;
import static io.crate.planner.optimizer.rule.FilterOnJoinsUtil.moveQueryBelowJoin;

public final class MoveFilterBeneathNestedLoop implements Rule<Filter> {

    private final Capture<NestedLoopJoin> joinCapture;
    private final Pattern<Filter> pattern;
    private volatile boolean enabled = true;

    public MoveFilterBeneathNestedLoop() {
        this.joinCapture = new Capture<>();
        this.pattern = typeOf(Filter.class)
            .with(source(),
                  typeOf(NestedLoopJoin.class)
                      .capturedAs(joinCapture)
                      // Can't apply this on OUTER JOINs as outer join actively produce new null rows
                      // We need to run the filter on top of these null rows to produce the correct results
                      .with(join -> !join.joinType().isOuter())
            );
    }

    @Override
    public boolean isEnabled() {
        return enabled;
    }

    @Override
    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }

    @Override
    public Pattern<Filter> pattern() {
        return pattern;
    }

    @Override
    public LogicalPlan apply(Filter filter,
                             Captures captures,
                             TableStats tableStats,
                             TransactionContext txnCtx,
                             Functions functions) {
        NestedLoopJoin join = captures.get(joinCapture);
        return moveQueryBelowJoin(filter.query(), join);
    }
}
